1. Field of the Invention
The present invention relates to the optoelectronic connectivity and the interconnection of an optical array to fiber optic cables.
2. Background Art
As processing speed increase and technology improves, data is being transferred at very high rates. However, one problem with high rate data transfer is that each leg in the process must be capable of the high rate or a bottleneck occurs. This problem holds true for data transfer within an integrated circuit, from one chip to another, from one integrated circuit board to another, and from system to system.
In the field of high-speed communications tools, increasing data transmission rates has been hindered by the limitations posed by fiber optics connectivity. In particular, increasing transmission density is difficult because the number of data transmission lines that conventional packaging technologies can handle is limited and subject to significant short-comings.
Present fiber optic transmission lines typically have up to twelve channels. If one or more channels on a conventional fiber optic transmission line malfunctions, the entire line must be replaced to restore full functionality of the line. Not only is there an increased cost associated with the maintenance, but the downtime in service can be catastrophic. Thus, there is a dire need for a way to increase the reliability for fiber optic transmission lines.
Also in the prior art, conventional vertical cavity surface emitting lasers (VCSELs) are mounted separately from the microprocessor that drives the VCSEL. This additional interface and configuration reduces the efficiency of the VCSEL and integrates another interface that is prone to maintenance and manufacturing problems, especially with the very high number of input/output (I/O) connectors with small tolerances for error. Therefore is a need for a way to hybridize VCSELs onto a processor substrate to improve the efficiency and transmission rates of the VCSELS.
There have been attempts to address the mismatch problem between optical arrays and optical connectors, but they have met with limited success. In general, there are many optical coupling devices that provide connectivity between fiber optic cables and terminate optical fiber cables, such as U.S. Pat. No. 5,909,526. There are also schemes for connecting electro-optics that employ complex coordination and alignment problems such as U.S. Pat. No. 5,579,426. But, the prior art still does not address interconnecting to an industry standard connector. As a connector type is adopted and approved as a standard, manufacturers and designers rush to incorporate the connector type to allow standardization in the industry. Thus far there has been a mismatch between the optoelectronics array technology having high density channels and the means for effectively incorporating and utilizing the array technology.
One of the difficulties in the emerging optical marketplace is that the market rejects innovative technologies because they are not compatible with existing technology. It is therefore commercially advantageous to integrate new technologies with existing infrastructure in order to be commercially accepted and used.
Thus, there is a need to provide an efficient and industry acceptable packaging system. There is a also a need for a way to bend the light from one plane to another in a minimum turn radius in order to keep the headroom adequate for packaging considerations. In addition, there is also a need for a way to hybridize VCSELs onto a processor substrate to improve the efficiency and transmission rates of the VCSELS. Thus, there is a dire need for a way to increase the reliability for fiber optic transmission lines. What is needed is a method and apparatus for utilizing the advantages of optical technology and providing a mechanism to efficiently interconnect to industry standard connectors such that the electronics industry can fully exploit the bandwidth, speed and efficiency of optics.
The invention is devised in the light of the problems of the prior art described herein. Accordingly it is a general object of the present invention to provide a novel and useful technique that can solve the problems described herein.
In one embodiment, the invention features a packaging system for two-dimensional optoelectronic arrays. The packaging system includes a heat spreader, a ceramic housing with embedded electrical traces, a solderless land grid array (LGA) including electrical contacts, an application specific integrated circuit (ASIC) including hybridized vertical cavity surface emitting laser (VCSEL) or detectors, a waveguide assembly including twelve individual waveguides and a waveguide housing, and a 2xc3x9712 ferrule for optical transition.
In a second embodiment, the present invention features a method for packaging two-dimensional optoelectronic arrays. The packaging method is easily scalable to various optoelectronic array configurations.
An object of the invention is a packaging system for a two-dimensional optoelectronic array, comprising a substrate with electrical interconnections, an application specific integrated circuit (ASIC) including the optoelectronic array, wherein the ASIC is electrically connected to the substrate. There is a waveguide assembly providing a flexible interface to the optoelectronic array on a first end and one or more optical connectors on a second end, wherein the waveguide assembly has two or more one-dimensional waveguide sheets, wherein the waveguide sheets match a footprint of the optoelectronic array on the first end and match a footprint of the optical connectors on the second end.
Another object is the packaging system, wherein the optoelectronic array is comprised of vertical cavity surface emitting lasers or photodetectors.
An additional object is the packaging system, wherein the optical connectors are ferrules and the waveguide sheets are combined to match a channel arrangement of the ferrules.
In addition, the packaging system, further comprising a housing assembly affixed to a first side of the substrate, wherein the housing assembly contains the optoelectronic array.
Yet a further object includes the packaging system, further comprising electrical connections on the substrate, wherein the electrical connections are selected from the group comprising a solderless land grid array (LGA) and a ball grid array (BGA). Also, further comprising a thermally conducting plate affixed to a second side of the substrate, and further comprising electronic circuitry on the substrate.
Objects include the packaging system, wherein the substrate is selected from the group consisting of a ceramic material and a printed circuit board. And, the packaging system, further comprising a cover on the ASIC fitting into a recess of the housing.
Furthermore, the optical waveguide assembly, wherein the waveguides are bendable within the waveguide sheets.
An object of the invention is a low-profile optical assembly for interfacing a two-dimensional optoelectronic array to an optical connector, comprising a substrate with electrical interconnections, an application specific integrated circuit (ASIC) with an optoelectronic array, wherein the ASIC is electrically connected to the substrate. There are two or more flexible waveguide sheets, wherein each of the waveguide sheets has an array end and a connector end. A plurality of one-dimensional waveguides are in each of the waveguide sheets, wherein each of the waveguides has an array end pitch at the array end and a connector end pitch at the connector end, and wherein the array end pitch matches a pitch of the optoelectronic array and the connector end pitch matches a pitch of the optical connector. Furthermore a waveguide housing at the array end of the waveguide sheets is used for retaining the waveguide sheets and aligning the waveguide housing to the optoelectronic array, wherein each of the waveguide sheets has an array end spacing at the array end and a connector end spacing at the connector end, and wherein the array end spacing matches a spacing at the optoelectronic array and the connector end spacing matches a spacing at the optical connector.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein we have shown and described only a preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by us on carrying out our invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention.